Ventilating device for centrifuge casings



June 4, 1940. F. w. KUNKEL VENTILATING DEVICE FOR CENTRIFUGE CASINGS Filed Dec. 30, 1938 I III Freaenbk M Aunke/ [NVENTQR r17 FORNEYS Patented June 4, 1940 UNITED STATES PATENT OFFICE VENTILATING DEVICE FOR CENTRIFUGE CASINGS Frederick W. Kunkel, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y.,

a a corporation of New Jersey Application December 30, 1938, Serial No. 248,466 a 6 Claims. (01. 210-03) The present invention relates to an improved form of centrifuging device which is particularly adaptedfor centrifuging nitro-cellulose or similar materials. a It is commonly known that in the productio of nitro-cellulose, there is a stage in the process when the product is easily denitrated by contact with air at high water content. This stageoccurs when the acid has been centrifuged off the 0 product and before the product has been soused in water. Such denitrated products, when dissolved in solvents, have portions which are rendered insoluble by partial denitration so that such products are not satisfactory when used as a dope for making photographic filmbase.

This denitration reaction can be controlled by product is lost in subsequent stages. Third, the

flow of air into and out of the centrifuge can be controlled in such a way that the product is maintained in essentially the same atmosphere from the time the centrifuge is loaded until it is emptied. This method is efiective because the large amount of acid which is removed during thecentrifuging serves as an effective dehumidifying agent and so produces a dry atmosphere inside the centrifuge before theprocess is. sufficiently free of acid to be susceptible to denitration. Therefore, ii the atmosphere is not changed, the product will not suffer from denitra tion. None of the above methods have however been entirely satisfactory.

The present invention has as one of its objects the provision of a centrifuging device which is ventilated to permit normal operation under any humidity conditions encountered in operation, without any loss of product quality.

Another object of the invention is the provision of a ventilating duct positioned within the centrifuging case and surrounding the basket spindle so that any leakage along the spindle is immediately exhausted from the casing, thus preventing outside air from reaching the nitro-celescaping into the room, and the flow of humid room air into the centrifuging basket is eliminated.

To these and other ends, the invention resides in certainimprovements and combinations of parts all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the specification.

In the drawing: 7 a i Fig. 1 shows a vertical sectional view through a centrifuging device of standard construction, showing the relation thereto of ,a ventilating duct and spindle seal construction constructed in accordance with the present invention.

Fig. 2 is a view similar to Fig. 1, showing a modified form of ventilating duct and spindle seal; and l l Fig. 3 is a plan view of the arrangement illustrated in Fig. 2.

Similar reference numerals throughout the various views indicate the same parts.

a The present invention is embodied in an apparatus based on the use of a centrifuging case which is made practically air tight. with the exception of the point where the basket spindle enters the case. Prior to the present invention no practical seal had been found for this point. To this end, the present invention provides a ventilating duct which extends across the casing. in such a way thatthe basket spindle passesdirectly through the duct. In this way, any leakage which tends to pass along the spindle will flow into the duct from which it is exhausted to a point outside the centrifuging casing. In this way, outside air is prevented from entering the centrifuge basket during the centrifuging operation, thus effectively preventing denitration of material in the basket. This arrangement also eliminates changes inthe atmosphere of the centrifuging casing when the centrifuge is in operation.

. However, when the casing door is opened for unloading, it is necessary to prevent the acid vaporsin the casing from escaping into the room,

and it is also necessary to prevent the humid room air from entering the centrifuging casing and basket. To this end the ventilating duct is placed so that the main vent opening thereof is along the back edge of the door and just under the casing cover or top. By such an arrangement, it has been possible to produce high quality nitro-cellulose when the humidity 'is high without resorting to expensive air conditioning or to more expensive reduction of centrifuging time.

The drawing shows a centrifuging device constructed in accordance with the present invention. The device shown in Fig. 1 comprises, in general, the, stationary. cylindrical outer casing formed to provide ,a bottom H, upwardly extending sides l2 and inclined or sloping top 4. A bottom discharge perforated centrifuging basket 15, of standard or well-known construction, is positioned within but out of contact with the casing. This basket is supported and r0- tated by means of a vertical spindle l6 which extends upwardly through an enlarged neck formed in the top portion, as clearly shown in Fig. 1. The casing is air tight, as later explained, except Where the spindle I6 passes through the neck I I.

In centrifuges of the type shown in the drawing, the spindle I6 is supported at the upper end in a suitable bearing, not shown. The spindle and basket thus hang in suspended relation from the. bearing much in the manner of the wellkhown'pendulum. With such a mounting, any eccentric loading of the basket I5 will cause the latter, and spindle I6, to sway from side to side, as is well-known. For this reason, the opening H3 in the neck I1 is made a sufficient size to accommodate the maximum swing without the spindle touching the sides of the neck.

However, to provide a seal or closure for the neck H, a set of annular plates 20, 2|, and 22 are provided, the plates 2|] and 2| being preferably of stainless steel, and the plate 22 being preferably aluminum. The plate is secured, by countersunk rivets 23, or other suitable fastening means, to an outturned portion or flange 24 formed on the neck l1, while the plate 2| is secured, by countersunk rivets 25, to the aluminum plate 22. The plates 20 and 2| are provided with registering central openings 28 and 21 respectively which are equal in size to the opening |8 of the neck H, as clearly shown in Fig. 1, and the contacting faces 28 of the plates are ground smooth so they may freely slide relative to each other. The plate 22, on the other hand, is provided with an opening which is slightly larger than the spindle IE to afford a substantially tight fit therearound, but of sufficient size that the plate, as well as the plate 2|, but not rotate with the spindle. When, however, the spindle I6 sways, as pointed out above, the plates 2| and 22 will move radially with the spindle l6, while the smooth ground contacting surfaces 28 afford a substantially air tight sliding connection between the plates 20 and 2|. As the spindle l6 has enlarged ends, not shown, which are of larger diameter than the opening 30 in the plate 22, the latter is split, as shown in Fig. 3, so that it may be positioned on the spindle. The plates 2m and 2| are so proportioned that even with the maximum sway of the spindle, the opening I8 will not be uncovered. The plates 28, 2| and 22 thus afford a relatively tight seal at the point where the Spindle l6 passes through the top of the casing, yet permits free radial movement of the spindle,

as isapparent from Fig. 1 of the drawing.

-As is well known, the rotation of the basket |5 will create a vacuum within the basket, the area of highest vacuum being of course along the spindle I6. With such a vacuum, outside air may be drawn along the spindle and through the opening 3|]. Such leakage of outside air into the casing may denitrate the nitro-cellulose, as pointed out above: In order to overcome this feature, the present invention provides a ventilating duct positioned within the casing, and arranged to vent such leakage to a point outside the casing, thus preventing denitration of the material in the basket l5.

In the preferred embodiment, this ventilating duct is' formed by means of a horizontal plate or baffle which is secured to the side wall I2 of the casing and extend part way across the casing, terminating short of the opposite side wall, as shown in Fig. 1. This bafile is spaced from the inclined top l4 but cooperation therewith to provide a ventilating duct 36 which converges tothe right. An exhaust connection 37 is secured to the side l2 and is in fluid communication with the duct 36 so that any air or fumes which are drawn into the duct may be suitably vented to a point outside the casing. Suitable exhaust equipment, not shown, is applied to the connection 31.

The baffle 35 is formed of any suitable material, preferably stainless steel, and is provided with an opening 38 through which the spindle l6 extends. This opening 38 is made of sufficient size to prevent engagement of the spindle l6, therewith even for maximum spindle sway. The opening 38 in the baflie is covered with a split sealing plate 39, similar to or identical with the plate 20, formed with an opening 40 which is slightly larger than the spindle l6 and through which the latter passes. The plate 39 is also movable radially with the spindle l6, sliding on the baflle 35, and thus cooperates with the plates 20, 2| and 22 to form a seal for the spindle at the points where it passes through the ventilating duct 36. It is apparent that the above-described arrangement will quickly, effectively, and continuously exhaust or withdraw any outside air which may tend to leak downward along the spindle l8 duringthe centrifuging operation, thus eliminating a changing atmosphere within the centrifuging casing.

The nitro-cellulose is loaded into-the basket l5 through a loading pipe 4| which is connected to a suitable source of supply,,not shown. Upon rotation of the spindle It, the acid is then removed from the material in the basket and is drained away through a discharge. pipe 42 in which is arranged a suitable trap, not shown, to

provide an air seal for the discharge line 42. At'

the end of the centrifuging operation, a door 44, hinged along one edge 45 to the top I4, is opened. A handle 46 may be provided for facilitating opening and closing of the door 44. A suitable gasket 41 may be provided for forming an air seal around the door when the latter is closed. In unloading, a suitable stick is inserted through the door 44 and the material which has now collected around the peripheryof the basket I5 is pried loose and discharged through a bottom opening, not shown, in the basket I5. This relatively acid-free nitro-cellulose then falls through a registering opening 48 formed in the bottom I and is conveyed by the pipe 49, connected to the opening 48, to a water bath in which the centrifuged nitro-cellulose is sousedf A. suitable Water seal, not shown, is provided in the pipe 49 to render the latter air tight to prevent leak,- ing into the centrifuging casing. By means of such an arrangement, the entire centrifuging casing is air tight except at the point where the spindle I6 passes through the opening 38 of the split plate 22.

However, when the door 44 is opened for the unloading operation, it is not only necessary to prevent the acid vapors Within the casing from escapinginto the room,'but also to insure that humid room air doesnot enter. the casing and basket and thus denitrate the centrifuged nitrocellulose. To this end, the ventilating duct 36 as shown in Fig. 1, provides a main vent opening 50 which is positioned along the-back edge 45 of a ventilating duct for the basket spindle, parts of the centrifuging casing.

corresponding to thOSEl in Fig. 1 will be designated by the same numerals. In this embodiment the left portion MA of the top is flat rather than inclined as in Fig. 1. An exhaust pipe or duct 55, connected to a suitable source of vacuum not shown, extends across the top 14A and terminates at 56 adjacent the hinged edge 45 of the door 44, as clearly shown in Fig. 2. The top wall 51. of the duct 55 is provided with a relatively large opening 58 through which the spindle It extends. The opening 58 is substantially the same size as the opening I8, Fig. 1, and is closed by the plates 20, 2| and 22, plate 20 being secured by countersunk rivets 25 tothe top 5'! of the duct 55. The spindle It extends through the opening 35 of the plate 22 in a manner described in connection with Fig. 1.

A U-shaped plate member fill, of the shape best shown in Fig. 3, is secured to and depends from the edges of an opening 6| formed in the top MA A horizontal baffle 01' plate 62 closes the bottom of the member 55 and cooperates therewith to provide a portion of the duct 55 which surrounds the spindle It, as shown in Fig. 2, The baffle 62 is also formed with an opening 63 which is covered by the split plate 39 through the opening 40 of which the spindle l6 passes, as above described. In this way leak age along the spindle I6 is exhausted through the duct 55. The right end of the U-shaped member 60 terminates adjacent the rear end 45 of the door to provide a main vent opening 64 for exhausting any leakage which may tend to enterthe casing when the door 44 is opened, as clearly indicated by the arrows in Fig. 2.

It is apparent from the above description that the disclosed ventilating duct provides an effective air seal for the basket and spindle during the centrifuging operation, and for the door during theunloading operation, thus preventing denitration of the cellulose nitrate in the centrifuging basket. It is also apparent from an inspection of Figs. 1 and 3 that a portion of the ventilating duct surrounds the basket spindle l5.

While one embodiment of the invention has been disclosed, it is to be understood that the inventive idea may be carried out in a number of ways. This application is therefore not to be limited to the precise detailsdescribed, but is intended to cover all variations and modifications and adapted to hold material to be centrifuged,

a basket driving spindle extending through said top, of a ventilating duct having a portion thereof positioned within said casing so that said spindle passes therethrough to provide an air seal for said spindle, and a main vent openingfor said duct adjacent said door.

2. In a centrifuging device, the combination with a casing having a top, a door in said top, a rotatable basket positioned within said casing basket driving spindle extending through said top, of a baffle extending across said casing in spaced relation to said top and cooperating therewith to provide an air seal duct through which said spindle passes, and a main vent opening for said duct adjacent said door, and an exhaust connection for said duct.

3. In a centrifuging device, the combination with a casing having atop, a door hinged along one edge to said top, a rotatable basket positioned within said casing and adapted to hold material to be centrifuged, a basket driving spindle extending through said top, of a horizontal baiile extending across said casing in spaced relation to said top and cooperating therewith to provide a ventilating duct through which said spindle passes to prevent air leaking along said spindle, a main vent opening for said duct adjacent said edge, and an exhaust connection for said duct. 4. In a centrifuging device, the combination with a casing having side and top walls, a rotatable basket positioned within said casing and and adapted to hold material to be centrifuged, a

adapted to holdmaterial to be centrifuged, a basket driving spindle extending through said top wall, a door hinged along one edge to said top wall adjacent said one side thereof, of a horizontal bafile operatively connectedlto one of said walls and extending across said casing in spaced relation to said top andcooperating therewith to provide a ventilating duct through'which said spindle passes, said duct providing an air seal for said spindle to prevent air leaking along said spindle from entering said basket, a main vent opening for said duct adjacent said one edge, and an exhaust connection on said side wall connected to said duct.

5. In a centrifuging device, the combination with an outer casing having a top, a rotatable basket positioned within said casing and adapted to hold material to be centrifuged, a spindle projecting exteriorly of said casing for supporting and rotating said basket, of a horizontal balfie extending across said casing in spaced relation to said top to provide a ventilating duct through which said spindle passes, said top and baflle being formed with registering openings for said spindle, plates surroundingsaid spindle and covering said openings to provide seals for said spindle where it passes through said top and said bafiie, said'plates being movable radially with said spindle but nonrotatable therewith, and an exhaust connection for said duct.

6. In a centrifuging device, the combination with an outer casing having atop, a rotatable basket positioned within said casing and adapted to hold material to be centrifuged, a supporting and driving spindle for said basket, a door hinged along one edge of said top, of a baffle extending horizontally across said casing in spaced relation to said top and cooperating therewith to provide a ventilating duct'through which said spindle passes, said top and baffle being formed with aligned openings for said spindle, apertured plates surrounding said spindle and overlying said opening to provide seals for said duct at the points where said spindle passes therethrough certain of said plates being slidable on said top and said bafile when said spindle moves radially, a main vent opening for said duct adjacent said one edge, and an exhaust connection for said duct.

FREDERICK W. KUNKEL. 

